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asm-generic: architecture independent readq/writeq for 32bit environment

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This provides unified readq()/writeq() helper functions for 32-bit
drivers.

For some cases, readq/writeq without atomicity is harmful, and order of
io access has to be specified explicitly.  So in this patch, new two
header files which contain non-atomic readq/writeq are added.

 - <asm-generic/io-64-nonatomic-lo-hi.h> provides non-atomic readq/
   writeq with the order of lower address -> higher address

 - <asm-generic/io-64-nonatomic-hi-lo.h> provides non-atomic readq/
   writeq with reversed order

This allows us to remove some readq()s that were added drivers when the
default non-atomic ones were removed in commit dbee8a0aff ("x86:
remove 32-bit versions of readq()/writeq()")

The drivers which need readq/writeq but can do with the non-atomic ones
must add the line:

  #include <asm-generic/io-64-nonatomic-lo-hi.h> /* or hi-lo.h */

But this will be nop in 64-bit environments, and no other #ifdefs are
required.  So I believe that this patch can solve the problem of
 1. driver-specific readq/writeq
 2. atomicity and order of io access

This patch is tested with building allyesconfig and allmodconfig as
ARCH=x86 and ARCH=i386 on top of tip/master.

Cc: Kashyap Desai <Kashyap.Desai@lsi.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Ravi Anand <ravi.anand@qlogic.com>
Cc: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Jason Uhlenkott <juhlenko@akamai.com>
Cc: James Bottomley <James.Bottomley@parallels.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Roland Dreier <roland@purestorage.com>
Cc: James Bottomley <jbottomley@parallels.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Hitoshi Mitake <h.mitake@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hitoshi Mitake
2012-02-07 11:45:33 +09:00
committed by Linus Torvalds
parent 27e74da980
commit 797a796a13
7 changed files with 66 additions and 60 deletions
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15
drivers/platform/x86/ibm_rtl.c
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@@ -33,6 +33,8 @@
#include <linux/mutex.h>
#include <asm/bios_ebda.h>
#include <asm-generic/io-64-nonatomic-lo-hi.h>
static bool force;
module_param(force, bool, 0);
MODULE_PARM_DESC(force, "Force driver load, ignore DMI data");
@@ -83,19 +85,6 @@ static void __iomem *rtl_cmd_addr;
static u8 rtl_cmd_type;
static u8 rtl_cmd_width;
#ifndef readq
static inline __u64 readq(const volatile void __iomem *addr)
{
const volatile u32 __iomem *p = addr;
u32 low, high;
low = readl(p);
high = readl(p + 1);
return low + ((u64)high << 32);
}
#endif
static void __iomem *rtl_port_map(phys_addr_t addr, unsigned long len)
{
if (rtl_cmd_type == RTL_ADDR_TYPE_MMIO)